Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Anesthesiology 398 and 466 > Lecture 10 Anesthesia in Horses > Flashcards

Lecture 10 Anesthesia in Horses Flashcards

1
Q

What are things you are interested when preping for horse anesthesia

A
  1. Presenting complaint
  2. Patient status
  3. Procedure
  4. IV catheter – jugular
  5. Wrap lower limbs
  6. Wash mouth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What premedications do you use for horses

A
  1. Alpha-2 agonist (one of the following):
    • Xylazine
    • Detomidine
    • Romifidine
  2. Opoid
    • Butorphanol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q
  1. Why would you use an alpha-2 agonist
  2. What are the onset of actions if given IV?
A
  1. Reasons:
    • sedation
    • anxiolysis
    • adjunct analgesia
    • muscle relaxation
  2. Onset of action 3-5 minutes (IV)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the onset of action and duration of action of:

  1. Xylazine
  2. Detomidine
  3. Romifidine
A
  1. Xylazine –
    • Onset of action ~3-5 minutes,
    • DOA ~30-60 minutes
  2. Detomidine –
    • Onset of action ~5 minutes,
    • DOA ~60 minutes
  3. Romifidine –
    • Onset of action ~15 minutes,
    • DOA ~2 hours
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the cardiovascular effects of alphla-2 agonists

A
  1. Initial hypertension then hypotension
  2. Bradycardia,
  3. 2nd degree atrio-ventricular block
    • P waves with no QRS
  4. ↓ cardiac output
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q
  1. What type of opioid is butorphanol
  2. Why use this opoid and not others
  3. What is another function of butorphanol other than analgesia?
A
  1. Mu antagonist/kappa agonist
  2. Other opoids are less mac sparing in horses and causes excitement
  3. Makes horse ‘plants’ feet
    • (They don’t move their and place them down)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do you use for induction on horses

A
  1. Ketamine
  2. benzodiazepine
    • midazolam or (this one used most commonly now)
    • diazepam
  3. Guafenesin (GG)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  1. What is guafenesin?
  2. What side effects does it have?
  3. How is it administered?
  4. Why administered that way?
A
  1. Central muscle relaxant
  2. Mild CV/respiratory effects
  3. 5% solution in 1 liter 5% dextrose
  4. 10% or > causes hemolysis & thrombophlebitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are the induction medications given?

A
  1. Bolus guafenesin 25-50mg/kg (250-500ml/horse)
  2. Then bolus Ketamine + benzodiazepine (midazolam or diazepam) (KM or KD)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How are horses intubated?

A

Blind intubation

  1. Extend head/neck in lateral recumbency
  2. Mouth speculum
  3. Tongue thru interdental space
  4. Over tongue, past cheek teeth, thru glottis
  5. Resistance?
    • Pull back slightly, rotate 90° & advance
    • DO NOT FORCE
  6. Inflate ET cuff
  7. Ventilatory support through Demand valve – IPPV with O2
    • They become hypoxic shortly after intubation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are horses positioned

A
  1. use hoist
  2. position on table
  3. Want to have even distribution on muscles
    • want to maintain blood flow
    • Dont want pressure on nerves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are different ways to administer Intra-op Analgesia

A
  1. Regional anesthesia
    • Can be limited by needing use of limbs for recovery
  2. Constant Rate infusions
    • Lidocaine
    • Ketamine
    • Dexmedetomidine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What Intra-op Monitoring is done in horses

A
  1. ECG
  2. SpO2
  3. EtCO2
  4. Inhalant agent monitoring –
    • Inspired/Expired Isoflurane
  5. Invasive (direct) BP monitoring always
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What must you remember when monitoring EtCO2 in horses

A

EtCO2 is 10-15 less than PaCO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the minimum MAP you want to maintain in horses

A

70mmHg (60 in small animals)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do you treat hypotension in horses

A
  1. IV fluids
  2. Multi-modal analgesia/anesthesia
    • To decrease amount of isoflurane used because it decreases BP
  3. Dobutamine CRI
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does dobutamine work to treat hypotension?

A
  • β1 > β2 - ↑ ↑ contractility & cardiac output, BP
    • Horses have a lot of sererve so can do this
    • Do not want peripheral vasoconstriciton so wont use norepinephrine and epinerphine to
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why do horses get a lot of Respiratory Insufficiency during anesthesia

A
  1. Anatomy, size & weight => alterations in PaCO2 & PaO2
  2. Compression atelectasis
    • Dorsal > lateral recumbency
  3. Anesthetics depress
    • respiratory drive
    • respiratory muscle function
    • ventilation (rate, volume)
    • response to hypercarbia/hypoxia
19
Q

What are 4 causes of hypoxemia in horses

A
  1. hypoventilation
  2. ventilation-perfusion (VA/Q)mismatching**
  3. right-to-left shunting of blood flow (Q)
  4. diffusion impairment
20
Q

Explain what happens if you have:

  1. V/Q = 1
  2. V/Q > 1
  3. V/Q < 1
A
  1. V/Q = 1 =>
    • ventitlation & perfusion well matched
  2. V/Q > 1 =>
    • lung ventilated but not well perfused (dead space ventilation)
  3. V/Q < 1 =>
    • lung well perfused but not ventilated
21
Q

Why is EtCO2 < PaCO2 in horses

A

30-40% TV goes to large airways not Involved in gas exchange

22
Q

What happens with large colon torsions

A
  1. Colon twists
  2. Inflates with air
  3. Will push up on diaphragm
  4. Decreases TV and can increase PCO2
23
Q

What will the V/Q ratio be for this

A
  • V/Q < 1
  • Lung perfused but not ventilated
24
Q

When is Intermittent Positive Pressure Ventilation used in horses?

A

Always!

25
Q

Why use Intermittent Positive Pressure Ventilation in horses?

A
  1. Hypoventilation & ↑PaCO2
  2. Consistent EtISO for stable anesthetic plane
  3. Maintain adequate PaO2
    • O2 supplementation + IPPV required
26
Q

What are the 4 aspects of recovering of anesthesia in horses

A
  1. Prevention from injury
  2. Positioning
  3. Airway & oxygen support
  4. Sedation/analgesia
27
Q

How are horses prevented from injury

A
  1. padded recovery stall
  2. head/tail ropes
  3. head helmet
  4. mats
28
Q

How are horses positioned for recovery

A
  • Pull lower forelimb forward
    • Takes pressure off triceps muscle
29
Q

What do you consider when giving analgesia after surgery

A
  1. Type, length
  2. Degree of pain
  3. Limitations in choices/method of analgesia
    • NSAIDS
    • Opioids
      • Limited by cost, side effects
30
Q

What kind of sedation can you do for recovery of horses

A
  1. Acepromazine or
  2. Alpha-2 agonists
31
Q
  1. Why use acepromazine for recovery sedation
  2. Negatives for using it?
A
  1. Positives:
    • Milder sedative compared to alpha-2
    • Less ataxia
    • Hypotension?
  2. Negatives:
    • No analgesia
    • Slow onset of action
    • IM or IV prior to disconnect from inhalant (need to plan to give before)
32
Q
  1. Why use Alpha-2 agonists for recovery sedation
  2. Negatives?
A
  1. Positives:
    • More profound sedation
    • Analgesia
    • Faster onset
  2. Negatives:
    • More ataxia
    • Oxygenation??
33
Q

Why use IPPV during recovery

A
  • Demand valve
    • Allows IPPV with O2
    • Rate of oxygen delivery
      • Up to 200L/min
  • Provides IPPV until return of spontaneous ventilation (ROSV)
    • Low inspiratory flows
    • Resistance to expiration
34
Q

What rate do you put horses at during recovery to provide Oxygen insufflation

A

5-15 L/kg/min

35
Q

What are causes of Airway Upper airway obstruction during recovery

A
  1. Displacement of the soft palate
  2. Nasal congestion
  3. Largyngeal hemiplegia
    • Upper airway surgery
    • High incidence in draft breeds
36
Q

Why do horses get Displacement of the soft palate

A
  • Obligate nose breathers
  • Extubate when swallowing
    • Allows replacement of SP
  • UA noise ‘snoring’
37
Q

What happens to the nasal mucosa during anesthesia in horses?

A

Nasal mucosa thickens from congestion/edema during anesthesia

38
Q

What can you do to help alleviate upper airway obstruction due to nasal congestion

A
  1. Phenylephrine (neosynephrine) to decrease congestion
  2. Provide ‘stent’ or alternate airway
    • Oral tracheal tube
    • Naso-tracheal tube
    • Naso-pharyngeal tube
39
Q

Why use Phenylephrine (neosynephrine) for recovery in horses

A
  • to decrease congestion
  • Significantly decreases the need for nasopharyngeal intubation
40
Q

By providing a ‘stent’ or alternate airway in horses during recovery, what are some reasons why you wouldnt or would have to be careful.

A
  • •Risk of damage to ET tube (expensive)
  • •Risk of damage to laryngeal structures
  • •Risk of obstruction due to kinking
  • •Affect ability to stand?
41
Q

What horses would you use stents or alternate airways

A
  1. Large amounts of GI reflux (colic)
  2. UA hemorrgage
  3. +/- draft horses
42
Q

What are the downfalls of Place naso-tracheal tube for recovery

A
  1. Risk of damage to laryngeal structures
  2. Risk of obstruction due to kinking
  3. Affect ability to stand?
43
Q

What are the downfalls of placing a naso-pharyngeal tube for recovery

A
  1. Risk of damage/hemorrhage of ethmoids
  2. Due to incorrect placement
    • Middle meatus vs ventral meatus
44
Q

What are Recovery Complications

A
  1. Upper airway obstruction leading to pulmonary edema
  2. Post-anesthetic neuropathy
    • poor positioning
  3. Post-anesthetic myopathy
    • poor positioning
    • Intra-operative hypotension
  4. Fracture

Anesthesiology 398 and 466 (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions